A couple of years ago I was driving home from Stafford through those 'naughty word' 50 mph roadworks on the M6 in my old diesel tourer and because I was bored I reset the mpg reading. For the entirety of the roadworks I got just over 50mpg.... driving at a steady 50mph..... life is just too short
By the time I got home it was down to 43, two days later it was back to the usual 36.
I now drive a 2.0 petrol car that does nearly the same, I miss the torque a bit but when unleaded is 10p cheaper I can live with it